The present invention relates to a mounting clamp and in particular to a mounting clamp for attaching accessories such as a pick-up truck cap to the bed of a pick-up truck.
Several clamps have been developed for use in securing accessories such as a pick-up truck cap, a tonneau cover, a cab spoiler, bed rails, etc., to a pick-up truck bed. One type of truck bed clamp includes two clamping parts pivotally connected to one another and adjustable by a threaded bolt. However, depending upon the thickness of the parts being clamped together, the two clamping surfaces may not be parallel to one another in the clamped position, compromising the clamping strength. This is due to the relative rotation of the clamp parts.
The disadvantage of pivotally connected clamp parts has been overcome by another clamp that provides two parts having a pair of engaging surfaces. During adjustment of the clamp, the two parts slide relative to one another along the engaging surfaces to securely fasten items to the truck bed. The sliding motion between parts allows the clamping surfaces to remain parallel to one another over a range of material thicknesses being clamped together. However, with such a clamp having only one pair of engaging surfaces between the two parts, the bolt used to hold the clamp parts together experiences high bending loads in addition to the tensile loads necessary to produce the clamping load.
Accordingly, it is an object of the present invention to provide an improved truck bed clamp configured to avoid bending loads in the attaching bolt and to maintain the clamping surfaces parallel to each other.
It is a feature of the clamp of the present invention to provide two clamp members in which one member is formed with a pocket into which a leg of the other member is slidably received. The result is two pairs of engaging surfaces between the two members which enables the received leg to be contacted on two sides by the receiving member. Contact on both sides of the received leg enables the internal bending moment in the clamp to be carried by the clamp members themselves rather than being carried through the securing bolt.
It is a further feature of the clamp of the present invention that the contact between the engaging surfaces is in the form of point contact rather than surface to surface contact. This results in less friction between the members. To further reduce the friction, the contact points are formed by bushings made of ultra-high molecular weight polyethylene which is self lubricating. When clamping loads are applied to the clamp members, resulting in internal bending stresses, the low friction between the clamp members facilitates relative movement of the clamp members.
It is a further feature of the clamp of the present invention that one or both of the clamping surfaces are formed with rubber bushings to avoid damage to the surfaces engaged by the clamp.
The two clamp members are attached to one another by a bolt slidably carried by one member and threadably received by the other. In a preferred embodiment of the clamp, the two clamp members are made of extruded aluminum. To provide increased strength to the threaded bolt attachment, a captured nut is mounted to the member receiving the bolt and both the bolt and the nut are made of steel. Steel has greater strength than the extruded aluminum for a threaded attachment.
One or both of the clamp members can be formed with means for mounting additional accessories to the clamp itself separate from the accessory mounted to the truck bed between the two clamping surfaces of the clamp members.
Further objects, features and advantages of the invention will become apparent from a consideration of the following description and the appended claims when taken in connection with the accompanying drawings.